When you choose to publish with PLOS, your research makes an impact. Make your work accessible to all, without restrictions, and accelerate scientific discovery with options like preprints and published peer review that make your work more Open.

PLOS BLOGS DNA Science

Thoughts on a Return of Polio

When a case of polio showed up in Rockland county, just north of New York City, in July 2022, and then polioviruses with the same genetic sequence as from the paralyzed man were found in three samples of wastewater collected from near his home, public health officials were alarmed. The man, from an Orthodox Jewish community with low vaccination rates in general, had not been immunized against polio.

Definitions from the World Health Organization kicked in.

The viral RNA sequence from the patient was close to that of oral polio vaccine, which is “live” (weakened, aka attenuated). He was infected with vaccine-derived polioviruses (VDPV). Then finding the telltale RNA sequence in wastewater elevated the situation to circulating vaccine-derived polioviruses (cVDPV). The US now joins 30 other nations experiencing a return of this infectious disease that was once thought to be nearly gone.

About 95 percent of people infected with wild polioviruses have no symptoms. The others develop fever, muscle weakness, headache, nausea, and vomiting. One to two percent progress to severe muscle stiffness and pain in the neck and back. For fewer than one percent, paralysis results. Before widespread vaccination against polio, mechanical ventilator devices called iron lungs were used to help children breathe, often for months.

The Role of Oral Polio Vaccine

The term “vaccine-derived” may suggest that the vaccine beckons an infectious disease to reappear, but that’s not quite what happens.

The new viruses differ slightly, in their RNA sequences, from the oral polio vaccine introduced in the 1950s. It consisted of attenuated virus that replicates along a child’s digestive tract, exiting with stool.

To develop the oral polio vaccine – aka OPV – Albert Sabin infected a series of animals with wild polioviruses. The strategy allowed mutations to accumulate that weakened the virus enough to stimulate an immune response in people without causing symptoms. Kids lined up in school cafeterias to eat the pink-stained, virus-bearing, sugar cubes that were the ingenious delivery vehicle for the vaccine. The children’s stool released the weakened polioviruses into sewage, and OPV spread protection even to those who hadn’t been vaccinated.

Gross, perhaps, but effective. However, the virus can mutate when it replicates, as live viruses do. It can become able, like its forebears, to take up residence in human neurons. Muscles weaken, in some cases to the point of the acute flaccid paralysis of poliomyelitis.

Vaxxed people are protected – that’s most of us. But communities with low vaccine uptake open a niche for new viral mutants. That’s what’s apparently happening now.

Said Dr. José R. Romero, Director of CDC’s National Center for Immunization and Respiratory Diseases when reporting the July 21 case, “Polio vaccination is the safest and best way to fight this debilitating disease and it is imperative that people in these communities who are unvaccinated get up to date on polio vaccination right away. We cannot emphasize enough that polio is a dangerous disease for which there is no cure.”

Vaccines can, theoretically, rid the world of polio. In 2013, experts from 80 nations signed The Scientific Declaration on Polio Eradication, which emphasized the danger of seeking control rather than eradication: “[W]e could expect up to 200,000 cases annually within a decade if the polio eradication effort is stopped, effectively reversing progress made over the past 25 years. Until eradication is achieved, we will always be at risk for poliovirus reappearing anywhere in the world.”

Only the injected, inactivated polio vaccine is given now in the US, because of the ability of OPV to mutate. And the component of the live vaccine that causes breakthrough cases was removed in 2014, which I covered for Medscape.

Vaccine Memories

I suspect that many people didn’t pay attention to the news about polio in the summer. Reasons varied: COVID fatigue, just another disease following monkeypox, or unfamiliarity with polio. Perhaps they don’t remember the pink sugar cube or one of many shots to protect against what were once called “the diseases of childhood.”

I had a bunch of those sicknesses that could in a matter of days empty a classroom, including measles for a month. So once I was old enough to understand vaccination, I could appreciate the protection that my younger sister had against measles, and then my kids against rubella and mumps. They put up with the spots of chickenpox, that vaccine initially reserved for children with leukemia and other risk factors that made the infection life-threatening.

Fortunately, vaccines vanquished polio in time for me. But one of my earliest memories, and one that contributed to my becoming a scientist, is of my mother’s fear of polio. In my baby book, in 1954, she wrote “April 15 – Polio Vaccine Perfected!!!”

She had good reason to celebrate. I wrote in The Scientist:

“For parents of young children in the early 1950s, summertime brought the terror of a fever that might explode into infantile paralysis,’ a fear propelled by images of Franklin D. Roosevelt’s battle with the disease. Although only 1 percent of infected individuals developed severe symptoms as the virus invaded spinal cord cells, the number of cases grew large enough to inspire a massive effort to develop a vaccine, including the founding of the March of Dimes in 1938 to specifically battle polio.

For those old enough to remember the Beatles, polio vaccines were part of childhood. By 1955, youngsters in many nations received injections of Jonas Salk’s inactivated polio vaccine. By 1962, children were lining up at school, tongues out to receive pink-stained lumps of sugar impregnated with Albert Sabin’s live, attenuated oral polio vaccine.”


Neither Salk nor Sabin sought patent protection for their inventions.

I had my polio vaccines in May, June, and October of 1956. Grateful parents throughout the U.S. realized that if enough people were vaccinated, active virus would have nowhere to infect, and polio would vanish. They had an intuitive understanding of the concept of herd immunity, if not by that name.

Thanks to the vaccine campaign, the last naturally occurring cases of polio in the United States were in 1979, although wild virus continued to come in from other places. By 1994, the WHO declared the Americas polio-free.

Encountering Polio During my Career as a Science Journalist

The recent Rockland county polio case made me think about my few connections to the disease.

I knew older siblings of friends who’d had it, and one friend in college and another in graduate school limped, a legacy from childhood polio.

In 1980, my college roommate Cheryl Adler was on the team that discovered the RNA sequence of a key gene of poliovirus that enables the virus to replicate, a landmark paper in Cell. I’d known her best as an early Deadhead and a great cook. Sadly Cheryl passed away young from a neurological disease. I last saw her at a Phish show.

In 1993, I met the two people who would become my co-authors for several editions of two human anatomy and physiology textbooks. We had half a day to kill in Chicago between flights to our publisher, so, being nerds, we visited the International Museum of Surgical Science. Enthralled, we christened the extensive exhibit of laboratory glassware a bong museum. Our laughter stopped, instantly, when we came upon an iron lung. We imagined a child trapped inside for months or even years as the bellows simulated moving lungs. Mesmerized, we appreciated, once again, the value of vaccines. How I wish the vaccine-hesitant had a grasp of the history of infectious diseases! Those of childhood are unfamiliar because vaccines vanquished them.

In 2014 I was the convocation speaker for the March of Dimes. FDR, who contracted polio at age 39 and lost use of his legs, originally called the organization the National Foundation for Infantile Paralysis. Donations at first were from wealthy celebrities, but when polio cases rose, Roosevelt sought help from the public. Singer Eddie Cantor jokingly asked the public to send dimes to the president. After nearly 3 million dimes showed up at the White House, the name was changed to the March of Dimes.

The first convocation speaker for the March of Dimes, in 1971, had been Jonas Salk. I was honored when the organization asked me to participate. I spoke at universities in four New York cities, compensated with an M&M-filled mug and a tee shirt.

CODA: Vaccine Hesitancy is Déjà vu All Over Again

I’ve published thousands of articles since getting my PhD in genetics in 1980. One from 2004 is chilling: Vaccines, Victims of Their Own Success, with the subhead “Why the most effective public health intervention evokes a mixed response from the public.” It appeared in The Scientist (I wrote for them for 17 years, until one day a new editor came in and fired all the regulars). Some of the quotes from experts, still at their institutions, could eerily have come today in the wake of the COVID pandemic:

“People in the United States want a quick solution, not prevention, so they prefer drugs to vaccines. Elsewhere, people are afraid of drugs and side effects, and prefer vaccines,” said Shan Lu, a primary-care physician at the University of Massachusetts Medical School who has worked on an HIV vaccine.


“In developed countries, we no longer have infectious diseases for which there are vaccines, so the risk of the vaccine is perceived to be greater than the risk of the disease. But that is true because the vaccine is being used,” said Stanley Plotkin, inventor of the rubella vaccine.

“In the 1950s, polio affected every neighborhood. Now natural polio is far removed from most peoples’ daily lives. But when a little girl in California develops side effects from polio vaccine, that hits the newspapers,” said Neil Herendeen, chief of pediatrics at Strong Memorial Hospital at the University of Rochester, New York.

“In the past, medicine was provided under a more paternalistic model, with the public trusting that they were receiving the appropriate service. Today, people participate more in their care, know more, and expect more,” said Mark Upfal, medical director at Detroit Medical Center Occupational Health Services.

Those concerns that resonate over the decades are challenging, and sometimes maddening, to unpack. But the underlying message that those opposed to vaccination seem to miss is the duty to think beyond themselves to act to protect the community.

Leave a Reply

Your email address will not be published. Required fields are marked *


Add your ORCID here. (e.g. 0000-0002-7299-680X)

Related Posts
Back to top